Liquid crystal display unit

ABSTRACT

A liquid crystal display unit includes: an insulating substrate; a counter insulating substrate; a liquid crystal put between the insulating substrate and the counter insulating substrate; a pixel matrix including plural pixels; and a peripheral circuit including a control section and an output section, for driving a gate line of a pixel TFT in each of the pixels. The pixel matrix and the peripheral circuit are integrally formed above the insulating substrate such that the output section is located closer to the pixel matrix than the control section. The liquid crystal display unit further comprises a light shielding metal disposed at an insulating-substrate side of the pixel TFT in each pixel, and a light shielding metal disposed at an insulating-substrate side of each TFT at least in the output section among TFTs in the peripheral circuit.

TECHNICAL FIELD

The present invention relates to a liquid crystal display unit, and inparticular, to a structure of a liquid crystal display unit in which adrive circuit and a pixel matrix are integrated in one body.

BACKGROUND

Liquid crystal display units used for certain applications such asprojectors (PJ) and head-up displays (HUD) are requested to have a smalldisplay size, in order to make the size of expensive optical components,such as a lens and a prism, smaller. Simultaneously, such liquid crystaldisplay units are further requested to cope with image qualitydeterioration due to irradiation of light since those liquid crystaldisplay units are irradiated with extremely strong light for a purposeof forming a bright image. In order to respond to the above requests,many of the liquid crystal display units used for the above applicationsare manufactured by a polycrystalline-silicon thin-film transistorprocess or a poly-Si TFT process. As the reasons, the following pointsmay be assumed. First, poly-Si TFTs have a field-effect mobility largerby 100 or more times than that of amorphous-silicon thin-filmtransistors (a-Si TFTs). Constituting a peripheral circuit of a liquidcrystal display unit by using poly-Si TFTs can make the liquid crystaldisplay unit small. Further, poly-Si TFTs have light sensitivity lowerthan that of a-Si TFTs. Accordingly, poly-Si TFTs are not likely tocause image quality deterioration due to a light leakage current.Generally, if a light leakage current takes place in a pixel TFT, apixel voltage tends to fluctuate, which causes lowering of contrast andflicker.

However, even in the case where poly-Si TFTs are used in such liquidcrystal display unit, if the poly-Si TFTs are irradiated with light withan illuminance of millions or more lux as in a projector (PJ), a lightleakage current in the poly-Si TFTs cannot be ignored. Since the poly-SiTFTs have a planar type structure, a channel section of each TFT isdirectly irradiated with light via a glass substrate, which may becomeone of the causes of the light leakage current. In order to cope withthe above problem, Japanese Unexamined Patent Application Publications(JP-A) No. H02-15676 proposes a technique to reduce a light leakagecurrent in such TFTs.

FIG. 12 shows a cross-sectional constitution of a poly-Si TFT disclosedin JP-A No. H02-15676. On a TFT substrate 101, a light shielding film320 made of a high melting point metal or its oxide is disposed beneatha polycrystalline silicon film 340 across an interlayer film 330.Further, a gate insulating film 350, a gate electrode 360, an interlayerfilm 370 and a wiring metal 380 are formed on the polycrystallinesilicon film 340. In a pixel section using a TFT having the abovestructure, a TFT channel section beneath a gate electrode 360 is notirradiated directly with light from the TFT substrate 101 side, wherebyit becomes possible to reduce a light leakage current in a TFT greatly.The above structure is mainly applied to TFTs in a pixel section, and isnot applied to TFTs in a peripheral circuit section. This is because alight shielding film which is disposed beneath a TFT channel section andhas conductivity can cause fluctuation in the threshold voltage of thecorresponding TFT. In a TFT in the pixel section, a voltage appliedbetween a source and a drain is lower than a voltage applied between asource and a gate. Accordingly, even if the above fluctuation of thethreshold voltage occurs, the TFT operates normally. On the other hand,in a TFT in the peripheral circuit section, in many cases, a voltagebetween a source and a drain and a voltage between a gate and a sourceare equal to each other. Accordingly, characteristics of the circuitfluctuate due the fluctuation of the threshold voltage, which causeslowering of the output voltage of the peripheral circuit section andmalfunction.

Therefore, for the peripheral circuit section, a method has beenproposed so as to shield it from light with a package member. FIG. 13 isa cross-sectional view of a liquid crystal display module for aprojector disclosed in JP-A No. H06-202160 (corresponding toUS2003/0025659A1). The liquid crystal display module includes a liquidcrystal panel composed of a TFT substrate 101, a CF substrate 102,liquid crystal 103 and a sealing member 104, and is structured such thatthe peripheral portion of the liquid crystal panel is covered with apackage member 106 made of a material which does not transmit light,such as a black mold resin or a ceramic. The package member 106 isprovided with an opening section 107 through which a pixel matrix 200can be irradiated with light. On the other hand, a peripheral circuit105 is arranged at a position covered with the package member 106,whereby the peripheral circuit 105 is not affected by light.

Although the problem caused by a light leakage current of a TFT isimproved by the above-mentioned method, another problem arises in thatthe cost of a liquid crystal display module becomes high. The reason isdescribed below. According to the above-mentioned method, it isnecessary to prepare a liquid crystal display module in which a pixelsection (pixel matrix) is not covered with a package member and aperipheral circuit is covered with the package member. Therefore, if adistance between the pixel section and the peripheral circuit in theliquid crystal panel is small, it is required to assemble the liquidcrystal panel and the package member with extremely high accuracy.However, the outside dimension of the liquid crystal panel includes atolerance in a cutting process, and the dimension of the package memberalso includes a tolerance. Furthermore, a tolerance takes place also ina process of superposing the liquid crystal panel and the packagemember. Each of the above tolerances is about 0.2 mm to 0.5 mm. In orderto surely prepare a structure that the pixel section is not covered withthe package member and the peripheral circuit is covered with thepackage member, each of the distance M1 and the distance M2 in FIG. 13is required to have a value equal to or larger than the total of theabove tolerances, and each of the distances M1 and M2 usually becomesabout 1 mm, where M2 represents a distance from an edge of the pixelmatrix 200 to an edge of the opening section 107 of the package member106, M1 represents a distance from an edge of the opening section 107 ofthe package member 106 to an edge of the peripheral circuit 105.Accordingly, a necessary distance from the edge of the pixel matrix 200to the edge of the peripheral circuit 105 becomes about 2 mm. In aliquid crystal panel including peripheral circuits 105 arranged at bothsides of the pixel matrix 200, functionless areas extending over a totallength of 4 mm need to be secured, which enlarges the liquid crystalpanel. If the external shape of a liquid crystal panel becomes large,the number of substrates of liquid crystal panels which can be laid outin one mother substrate decreases. Therefore, especially, in the case ofa liquid crystal panel for a head-up display, whose display area has adiagonal dimension being about 2 inches and is larger than that of aliquid crystal display unit for a projector, the reduction of the numberof substrates which can be laid out in one mother substrate becomesextremely large, which increases cost.

As a method of solving the above problems, the method disclosed by JP-ANo. 2008-165029 may be used. In this method, a light shielding film isarranged for each of TFTs in a pixel section and TFTs in a peripheralcircuit, wherein an earth potential is applied to the light shieldingfilm for each TFT in the pixel section and a gate potential is appliedto the light shielding film for each TFT in the peripheral circuit.According to this method, there is no need to surely cover theperipheral circuit with a light shielding package member, and a panelsize can be made small.

Further, as a technique to lower the cost of a liquid crystal displayunit, for example, as disclosed by JP-A No. 2006-351165 (correspondingto US2006/0262074A1), a method of forming TFTs in a pixel section andTFTs in a peripheral circuit to be poly-Si TFTs of a single conductivitytype may be used. FIG. 14 shows a circuit diagram of a gate driverconstituted by p-type poly-Si TFTs, which is disclosed in JP-A No.2006-351165, where Tr1 to Tr8 represent transistors, IN represents inputsignal, OUT represents output signal, CL1 and CL2 represent clocksignal, RST represents reset signal, VDD represents a power source, VSSrepresent the ground, and N represents a node.

In the case where the light shielding method for TFTs disclosed in JP-ANo. 2008-165029 is combined with the method of constituting a peripheralcircuit with poly-Si TFTs of a single conductivity type disclosed inJP-A No. 2006-351165, an area necessary for forming a peripheral circuitincreases greatly. As a result, it turns out by the inventor'sinvestigation that the panel size is hardly miniaturized. The reasonsare described below.

In the method disclosed in JP-A No. 2008-165029, a light shielding filmdisposed beneath each TFT constituting the peripheral circuit is neededto be provided with the same electric potential with a gate electrode ofthe corresponding TFT. In an example of the circuit shown in FIG. 14,eight TFTs are used in one block constituting a scanning circuit, wherea gate-electrode electric potential is common to both of TFTs Tr1 andTr2, a gate-electrode electric potential is common to both of TFTs Tr3and Tr4, and similarly, a gate-electrode electric potential is common toboth of TFTs Tr7 and Tr8. In consideration of the above situations, thelight shielding films are provided as at least five separatedisland-shaped films each independent electrically from the others. FIG.15 is a layout diagram showing a single TFT including a contact hole 325adapted to connect a gate electrode 360 and a light shielding film 320,and FIG. 16 shows a cross-sectional view taken along the line XVI-XVI inFIG. 15. In FIGS. 15 and 16, 101 represents a TFT substrate, 330 and 370represent interlayer films, 340 represents a polycrystalline siliconfilm, 350 represents a gate insulating film, 360 represents a gateelectrode, and 380 represents wiring metal. In the example shown inhere, the light shielding film 320 is electrically connected with thegate electrode 360 through the contact hole 325 which penetrates theinterlayer film 330 and the gate insulating film 350. That is, it isnecessary to form such a contact hole 325 in each of the light shieldingfilms being the five separated island-shaped films. Accordingly, an areaneeded to constitute the circuit increases greatly. Since a gate driverfor one block is needed to be arranged within the same width as a pixelpitch, an amount of an increase in a circuit area becomes appreciablylarger in a liquid crystal display unit with a small pixel pitch.

Further, in a liquid crystal panel in which the circuit is constitutedwith TFTs of a single conductivity type, a bootstrap method is used suchthat the amplitude of an output voltage may become equal to a powersource voltage. In the circuit shown in FIG. 14, the gate potential ofTFT Tr7 is lowered by the bootstrap method (in the case of using p-typeTFTs), and it operates such that the amplitude of output signal OUTbecomes equal to the voltage between power sources VDD and VSS. Ifdescribing a little in more detail, in the bootstrap method, first, theelectric potential of a node N connected to the gate of TFT Tr7 is madeto an electric potential to make TFT Tr7 become a conduction state.Thereafter, the node N is made into a floating state, and clock signalCL1 transits to a low level, whereby the electric potential of the nodeN lowers together with an electric potential change of a sourcepotential (OUT) by a capacitive coupling between a source and a gate ofTFT Tr7. Here, if the method disclosed in JP-A No. 2008-165029 isapplied to this circuit, a light shielding film which overlaps with thesource and drain regions of TFT Tr7 in a planar view is disposed beneaththe TFT Tr7, and the light shielding film is connected to a gateelectrode electrically. Accordingly, the parasitic capacitance of thenode N becomes extremely large. This is because TFTs Tr6 and Tr7 areconstituted to form an output section in this circuit and the channelwidth of TFT Tr7 is set to become extremely large in order to charge anddischarge a gate line of a pixel region serving as a load within a giventime period. If the parasitic capacitance of the node N is large, ittakes a long time to provide the node N with an electric potential tomake TFT Tr7 to a conduction state. Accordingly, another problem arisesin that a high speed operation cannot be performed. Even if theperipheral circuit is constitute with n-type TFTs, these problems occursimilarly.

The present invention seeks to solve the problems.

SUMMARY

In view of the above-described problems, there are provided illustrativeliquid crystal display units as embodiments of the present invention. Insuch liquid crystal display units, a peripheral circuit constituted withTFTs is formed integrally together with pixels in one body on the samesubstrate, and the liquid crystal display units are irradiated withextremely strong light from a light source. The illustrative liquidcrystal display units provide a structure which does not causeoperational failures of the peripheral circuit due to strong light,makes the size of a liquid crystal panel small, and can realize areduced cost.

An illustrative liquid crystal display unit relating to one aspect ofthe present invention comprises: an insulating substrate; a counterinsulating substrate facing the insulating substrate; and a liquidcrystal put between the insulating substrate and the counter insulatingsubstrate. The liquid crystal display unit further comprises a pixelmatrix including a plurality of pixels each including a pixel capacitorand a pixel TFT; and a peripheral circuit including a control sectionand an output section, for driving a gate line of the pixel TFT in eachof the pixels, where each of the control section and the output sectionincludes TFTs. The pixel matrix and the peripheral circuit areintegrally formed in one body and formed on the insulating substrate,where the output section is located closer to the pixel matrix than thecontrol section when being viewed from a normal direction of theinsulating substrate. The pixel TFTs of the pixels and the TFTs in theperipheral circuit have a top-gate structure. The liquid crystal displayunit further comprises a light shielding metal (or a light shieldingfilm) disposed at an insulating-substrate side of the pixel TFT in eachof the pixels, and a light shielding metal disposed at aninsulating-substrate side of each of the TFTs at least in the outputsection among the TFTs in the peripheral circuit. Optionally, thecontrol section may include a TFT at the insulating-substrate side ofwhich a light shielding metal is not disposed.

In the illustrative liquid crystal display unit, the TFTs in theperipheral circuit may be TFTs of a same conductivity type. The TFTs inthe output section may include a first TFT whose gate voltage is to bestepped up or stepped down by a bootstrap method, and the lightshielding metal formed at the insulating-substrate side of the first TFTmay have a same electric potential as an electric potential of an outputterminal of the output section.

In the illustrative liquid crystal display unit, the TFTs in theperipheral circuit may include a second TFT at the insulating-substrateside of which a light shielding metal is disposed, where the second TFTis different from the first TFT. The light shielding metal disposed atthe insulating-substrate side of the second TFT may have a same electricpotential as that of a source electrode of the second TFT.

The illustrative liquid crystal display unit may further comprise apackage member made of a material which does not transmit light, whereinthe package member covers the insulating substrate and the counterinsulating substrate, and includes an opening section formed thereon.Further, an edge surface of the opening section may overlap with theoutput section when being viewed from the normal direction of theinsulating substrate. Further, the edge surface of the opening sectionmay be located in the middle of a pixel-matrix-side edge of the controlsection and a peripheral-circuit-side edge of the pixel matrix whenbeing viewed from a normal direction of the insulating substrate.

Other features of illustrative embodiments will be described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the accompanying drawings which are meant to be exemplary,not limiting, and wherein like elements numbered alike in severalfigures, in which:

FIG. 1 is a plan view illustrating the structure of a liquid crystaldisplay unit pertaining to one embodiment of the present invention;

FIG. 2 is a cross-sectional view illustrating the structure of a liquidcrystal display unit pertaining to one embodiment of the presentinvention;

FIG. 3 is a block diagram illustrating the constitution of a liquidcrystal display unit pertaining to one embodiment of the presentinvention;

FIG. 4 is a block diagram illustrating the constitution of a gate driverapplicable to a liquid crystal display unit pertaining to one embodimentof the present invention;

FIG. 5 is a cross-sectional view illustrating the structure of a liquidcrystal display unit pertaining to one embodiment of the presentinvention;

FIG. 6 is a circuit diagram illustrating the constitution of a gatedriver applicable to a liquid crystal display unit pertaining to oneexample of the present invention;

FIG. 7 is a plan view illustrating a layout of a part of a gate driverapplicable to a liquid crystal display unit pertaining to one example ofthe present invention;

FIG. 8 is a cross-sectional view illustrating the structure of a liquidcrystal display unit pertaining to one example of the present invention;

FIG. 9 is a cross-sectional view illustrating the structure of a liquidcrystal display unit pertaining to one example of the present invention;

FIG. 10 is a schematic diagram illustrating an arrangement pattern oflight shielding films of a liquid crystal display unit pertaining to oneexample of the present invention;

FIG. 11 is a timing chart illustrating operations of a gate driverapplicable to a liquid crystal display unit pertaining to one example ofthe present invention;

FIG. 12 is a cross-sectional view illustrating the structure of aconventional liquid crystal display unit;

FIG. 13 is a cross-sectional view illustrating the structure of aconventional liquid crystal display unit;

FIG. 14 is a circuit diagram illustrating the constitution of a gatedriver of a conventional liquid crystal display unit;

FIG. 15 is a plan view illustrating a layout of a part of a gate driverof a conventional liquid crystal display unit; and

FIG. 16 is a cross-sectional view illustrating the structure of aconventional liquid crystal display unit.

DETAILED DESCRIPTION

Illustrative liquid crystal display units will be described below asembodiments of the present invention with reference to the drawings. Itwill be appreciated by those of ordinary skill in the art that thedescription given herein with respect to those figures is for exemplarypurposes only and is not intended in any way to limit the scope ofpotential embodiments may be resolved by referring to the appendedclaims.

The illustrative liquid crystal display unit is prevented fromoccurrence of image quality deterioration and malfunction of a gatedriver integrally formed with pixels on a TFT substrate even if theliquid crystal display unit is irradiated with extremely strong light.

Further, in the illustrative liquid crystal display units, it becomespossible to realize to use a liquid crystal panel with a smalldimension, and the cost can be made low.

Next, description is given in detail to one embodiment of the presentinvention with reference to the drawings. A size and a scale for eachconstitutional component of each of the drawings are appropriatelyadjusted in order to secure the visibility of the drawings.

FIG. 1 is a plan view illustrating a structure of a liquid crystaldisplay unit pertaining to the present embodiment. This liquid crystaldisplay unit has a constitution in which a liquid crystal panel 100including two facing insulating substrates is covered with a packagemember 106 made of a material which does not transmit lightsubstantially. The package member 106 includes an opening section 107where a display section of the liquid crystal panel 100 is not coveredand is exposed. To the liquid crystal panel 100, a flexible board 108for supplying drive signals from an external device or component isconnected. FIG. 2 is a cross-sectional view illustrating across-sectional structure taken along the line II-II in FIG. 1. Theliquid crystal panel 100 has a constitution in which a TFT substrate 101and a CF substrate 102 are superimposed on each other. In the TFTsubstrate 101, TFTs are formed on an insulating substrate, such as aglass substrate, and, in the CF substrate 102, color filters (CF) areformed on another insulating substrate, such as a glass substrate. Aliquid crystal 103 is put and sealed in a space surrounded by the TFTsubstrate 101, the CF substrate 102, and a sealing member 104 whichpastes the TFT substrate 101 and the CF substrate 102 together. On theTFT substrate 101, there are formed a pixel matrix 200 and a peripheralcircuit 105 each including TFTs, where the pixel matrix 200 includesplural pixels arranged in matrix, and the peripheral circuit 105 isconfigured to drive the pixel matrix 200, especially a gate line of thepixel TFT in each pixel. The pixel matrix 200 is located at a positionof the opening section 107 of the package member 106, and is not hiddenby the package member 106. When being viewed from the normal directionof the TFT substrate 101, there is a distance “d” between the edge ofthe pixel matrix 200 and the edge of the opening section 107 of thepackage member 106.

Although the peripheral circuit 105 is arranged on two sides of thepixel matrix 200 in the example shown in FIG. 2, the peripheral circuit105 may be arranged at only one side. Further, the sealing member 104may be arranged at a position where the sealing member 104 is made tooverlap with the peripheral circuit 105 in a planar view, or at aposition between the pixel matrix 200 and the peripheral circuit 105.Furthermore, in the case where the liquid crystal panel itself is notrequested to have a function to select color, it is needless to say thatthere is no need to provide a color filter to the CF substrate 102.

FIG. 3 is a block diagram showing a constitution of the liquid crystalpanel 100. The liquid crystal panel 100 includes a pixel matrix 200,gate drivers 600 being peripheral circuits, and a data driver 800. Thepixel matrix 200 includes a matrix of pixels each including at least apixel TFT 300 and a pixel capacitor 500. Each of the gate drivers 600serves as a peripheral circuit to drive gate lines (G1-G3) connected tothe respective gate terminals of the pixel TFTs 300. The data driver 800drives data lines (D1-D4) connected to the respective drain terminals ofthe pixel TFTs 300. The gate driver 600 is constituted with TFTs, andthe data driver 800 is constituted with TFTs or ICs made of acrystalline Si. The pixel TFTs 300 and TFTs constituting at least thegate driver 600 are poly-Si TFTs of a single and same conductivity type.The gate driver 600 can employ the structure illustrated in FIG. 4.

The circuit illustrated in FIG. 4 is driven by using two phase clocksCLK1 and CLK2, power sources VGH and VGL and a non-illustrated startsignal. The gate driver 600 has a constitution in which blocks 630 eachincluding a control section 610 and an output section 620 are connectedin series, and is configured to transfer a start signal sequentially tothe next block in synchronization with clocks CLK1 and CLK2. The outputs(OUT_(n−1) to OUT_(n+2)) of the blocks 630 are connected to therespective different gate lines of the pixel matrix 200. Accordingly,the number of the blocks 630 of the gate driver 600 is made equal to orlarger than the number of the gate lines of the pixel matrix 200. FIG. 4shows circuits of four blocks. For example, in the case where the blockwith an output indicated with OUT_(n−1) is a block of the first stage, astart signal is supplied to a terminal indicated with OUT_(n−2) in FIG.4. The output section 620 is constituted with at least two TFTs.Although FIG. 4 shows an example where the output section 620 isconstituted with n-type TFTs, it may be constituted with p-type TFTs.

FIG. 5 illustrates a cross section in the vicinity of an edge B of theopening section 107 of the package member 106 of the liquid crystaldisplay unit. Beneath (referred to as at a lower side, at a TFTsubstrate 101 side, or at a back-channel side) each of the pixel TFTs ofthe pixel matrix 200 and TFTs constituting the output section 620 of thegate driver 600, a light shielding film 320 (or a light shielding metal)is disposed at a position where the light shielding film 320 overlapswith (or hides) at least a channel section of a corresponding one of theTFTs in a planar view (namely, when viewed from the normal direction ofthe TFT substrate 101). The TFTs which constitute the control sections610 include a TFT or TFTs at the TFT-substrate side of which the lightshielding film 320 is not disposed. The light shielding film 320disposed beneath each of the TFTs which constitute the output section620 is made electrically independent of other components in the otherblocks 630 of the gate driver 600, and is connected electrically to theoutput terminal of the corresponding one of the blocks 630. The lightshielding film 320 disposed beneath each of the pixel TFTs may be madein the state of electrically floating, or in the state of being providedwith the same electrical potential with gate lines. Further, the outputsection 620 of the gate driver 600 is arranged between the pixel matrix200 and the control section 610. Then, an edge surface of the openingsection the package member 106 overlaps with the output section 620 whenbeing viewed from the normal direction of the TFT substrate 101, wherethe edge surface of the opening section is located in the middle of apixel-matrix-side edge of the control section 610 and aperipheral-circuit-side edge of the pixel matrix 200. Concretely, theedge B of the opening section of the package member 106 is set to bedisposed between the edge A near to the pixel matrix 200 among the edgesof the control section 610 and an edge C near to the output section 620among the edges of the pixel matrix 200. The value of each of a distanceDab between the edge A and the edge B and a distance Dbc between theedge B and the edge C is made a value near to the total value of thedimension accuracy of the outer shape of the liquid crystal panel 100,the dimension accuracy of the package member 106, and the positionaccuracy at the time of incorporating the liquid crystal panel 100 intothe package member 106.

The above-described structure of the liquid crystal display unit of thepresent embodiment, enables to realize a liquid crystal display unit byusing a liquid crystal panel with a small dimension, where the liquidcrystal display unit does not cause image quality deterioration andmalfunction of the gate driver circuit constituted with TFTs even underthe condition that the liquid crystal display unit is irradiated withextremely strong light. The reasons for it are described below.

If a liquid crystal display unit in which a TFT is disposed in eachpixel is irradiated with extremely strong light, a leakage current dueto light flows through the pixel TFT, and a voltage held in the pixelcapacitor fluctuates. This voltage fluctuation may cause flicker,crosstalk occur or lowering of contrast. However, in the structure ofthe present embodiment, since a light shielding film is disposed at theback-channel side (the TFT-substrate side) of each of the pixel TFTs,the channel section is not irradiated with light directly. Accordingly,it becomes possible to reduce leakage currents due to light greatly,thereby preventing degradation of image quality.

Further, if TFTs constituting a gate driver are irradiated withextremely strong light, a light leakage current flows through the TFTsconstituting the circuit. Accordingly, an electric potential in thecircuit may fluctuate, which may cause malfunction. However, in theliquid crystal display unit of the present embodiment, the controlsection 610 of the gate driver is shielded from light by the packagemember 106 and the output section 620 is shielded from light by thelight shielding film 320. Accordingly, the TFTs constituting the gatedriver are not irradiated with light directly. Therefore, malfunctiondue to a light leakage current does not occur.

Furthermore, if an interlayer film 330 between a light shielding film320 and the polycrystalline silicon film of a TFT constituting theoutput section 620 is made thinner, the threshold voltage of the TFTfluctuates due to the influence of the light shielding film 320. Forexample, in the case that n-type TFTs are used, with a change of theelectric potential of the light shielding film 320 to be larger ascompared with the electric potential of the source electrode of the TFT,the threshold voltage of the TFT changes so as to become small. With thechange of the electric potential of the light shielding film 320 in theopposite direction, the threshold voltage changes so as to become large.In a gate driver constituted with only TFTs of a single conductivitytype, there may be a case where the electric potential of each of thedrain electrode and the source electrode of the TFT changes more thanthe range of an electric source voltage. Accordingly, in the case wherethe light shielding film 320 is made in a state of floating, theelectric potential of the light shielding film 320 fluctuates greatlydue to the capacitive coupling with a drain electrode, and the thresholdvoltage of the TFT also fluctuates greatly, which may cause malfunction.However, in the constitution of the present embodiment, since thecontrol section 610 is not directly irradiated with light, there is noneed to dispose the light shielding film 320 for each TFT in the controlsection 610, and a threshold fluctuation does not occur. Further, in theTFTs constituting the output section 620, since the same voltage as thatat the output terminal is applied to the light shielding film 320, theamount of fluctuation of the threshold voltage can be controlled.

In the circuit illustrated in FIG. 4, since n-type TFTs are used, one ofthe TFTs constituting the output section 620 is adapted to output ahigh-level pulse one time during one flame period being a writing periodduring which the liquid crystal display unit writes in video signalswith the number corresponding to one screen, and another one of the TFTsis adapted to perform an operation to output a low-level voltage otherthan a period to output a pulse. In the structure of the presentembodiment, since the electric potential of the light shielding film 320is made the same with the electric potential of the output terminal, ina period to output a high-level pulse, with an increase of the outputvoltage, the electric potential of the light shielding film also becomeshigh and the threshold voltage of the TFT becomes small, which can makea rise time of the electric potential shortened. In a period duringwhich the output becomes a low level, the electric potential of thelight shielding film becomes low, the threshold voltage of the TFTbecomes high, but a voltage between the gate and the source necessaryfor outputting a low level is not large. Therefore, it is possible toactuate the TFT sufficiently even if the threshold voltage becomes high.Further, if the amount of fluctuation of the threshold voltage due tothe electric potential of the light shielding film has been evaluatedbeforehand, even in the case where the threshold voltage fluctuates, itbecomes possible to cope with the fluctuation by setting a power sourcevoltage to a value capable of outputting a low-level voltagesufficiently. Furthermore, although the light shielding film is made tohave a parasitic capacitance between it and each of the channel section,the source electrode, and the drain electrode of the TFT, the channelwidth of the TFT constituting the output section 620 is set to a largesize enough to drive gate lines. It makes possible for the lightshielding film to charge and discharge the parasitic capacitance thereofwithin a short time. Accordingly, the highest operation frequency of thecircuit is not restricted.

In the case where the gate driver is shielded from light by the packagemember, the size of the liquid crystal panel becomes large. As a result,the cost of the liquid crystal display unit becomes high. The reasonswhy the size of the liquid crystal panel is needed to be made large, areas follows. That is, even if a tolerance takes place on the outer figureof a liquid crystal panel, the dimension of the package member, thepositional accuracy at the time of incorporating the liquid crystalpanel into the package member, and the like, the gate driver is requiredto be covered always with the package member and the pixel matrix isrequired to be not covered always with the package member. In order toattain the above requirements, it is necessary to set each of a distancebetween an edge of the opening section of the package member and an edgeof the gate driver and a distance between an edge of the opening sectionof the package member and an edge of the pixel matrix to a value near tothe total value of the above tolerances. Usually, since the total valueof those tolerances becomes about 1 mm, there is a need to providefunctionless areas extending over a length of about 2 mm in total at aposition between the pixel matrix and the gate driver. Accordingly,since the size of the liquid crystal panel becomes large in proportionto the length of the functionless areas, the number of liquid crystalpanels capable of being laid out on a single mother substrate decreases.As a result, the cost becomes high. However, in the liquid crystaldisplay unit of the present embodiment, a light shielding film isdisposed for each TFTs constituting the output section in the gatedriver, and the output section is arranged at a middle position betweenthe control section and the pixel matrix.

Moreover, in the area of the circuit section constituting the gatedriver, an area for arranging the TFTs constituting the output sectionbecomes the largest. The reason is that since there is a need to chargeand discharge the gate lines becoming a load within a certain giventime, the channel width of the TFTs constituting the output sectionbecomes extremely large as compared with others. If an example is shown,in the case where a liquid crystal display unit with pixels of VGAresolution (640×480) is driven with a frame frequency (the inversenumber of one frame period) of 60 Hz, when the channel width of the TFTsof the control section is 5 μm, the channel section of the TFTs of theoutput section may become 500 μm. Of course, the channel width of a TFTchanges depending on the characteristic of the TFT and a devicestructure to determine the parasitic capacitance of the gate line.However, the situation that the channel width of the TFTs of the outputsection becomes large remarkably as compared with others, does notchange. In the liquid crystal display unit of the present embodiment,since a light shielding film is disposed for each TFT at least in theoutput section, there is no need to cover the output section with thepackage member. Since this output section can be arranged at a positionbetween the pixel matrix and the control section, it becomes possible tomake the size of the liquid crystal panel small in proportion to an areafor disposing at least the circuit of the output section. As the numberof pixels increases, the size of the TFTs of the output section isrequired to be made large. Further, the blocks of the gate driver needto be disposed within the width of a pixel pitch. Accordingly, as apixel pitch becomes smaller, the length to arrange a circuit becomeslonger. Therefore, the higher, the definition of a liquid crystaldisplay unit is, the larger, this effect becomes.

Examples

Description is given to an example of the illustrative liquid crystaldisplay units. FIG. 6 illustrates a circuit diagram corresponding to oneblock of a gate driver constituted by only the n-type TFTs having beendescribed in the above embodiment. This circuit is driven with two phaseclocks CLK1 and CLK2, an input signal IN, and two power sources VGH andVGL. Here, it is determined that VGH is a power source at the highervoltage side and VGL is a power source at the lower voltage side.Further, in the case where a block concerned is the first stage amongmultiple cascade-connected blocks, an input signal IN for the firststage block is a start signal, and an input signal IN for each of blocksother than the first stage block is an output from a previous stageblock. The relationship between clocks connected separately to thecontrol section 610 and the output section 620 changes for each block.In each of the blocks connected separately before and after the blockshown in FIG. 6, the clock CLK2 is connected to the control section, andthe clock CLK1 is connected to the output section. The amplitude rangeof each of the clocks CLK1 and CLK2 and the start signal becomes avoltage between those of VGH and VGL.

One block of the gate driver is constituted with a control section 610and an output section 620, the output section 620 is constituted withtwo TFTs Tr1 and Tr2, and the control section 610 is constituted withthree TFTs Tr3, Tr4, and Tr5. The gate voltage of TFT Tr1 constitutingthe output section 620 is configured to be stepped up by a bootstrapmethod so as to become a voltage higher than VGH. The capacitor Cb has acapacitance for the stepping up. However, in the case where a parasiticcapacitance between the source and the gate in TFT Tr1 is large enough,there is no need to dispose necessarily the capacitor Cb.

As stated in the description of the above embodiment, a light shieldingfilm is disposed beneath each of TFTs Tr1 and Tr2 constituting theoutput section 620, and the output section 620 is disposed between thecontrol section 610 and the pixel matrix in a planar view. FIG. 7illustrates a layout of the output section 620, and FIGS. 8 and 9illustrate the respective cross sections taken along the respectivelines VIII-VIII and IX-IX in FIG. 7.

Next, description is given to a cross-sectional structure of the outputsection 620 with reference to FIG. 8. On a TFT substrate 101 made of amaterial which has insulation properties such as glass etc. and cantransmit light, light shielding films 320 are formed and patterned. Forthe light shielding films 320, a material with a high melting point,such as W, Cr, Ti, and an alloy containing these metals, may be used. Onthe light shielding films 320, an interlayer film 330 to be used as abase layer of polycrystalline silicon films is formed. For theinterlayer film, a film of SiO₂ or SiN_(x), or a laminated filmincluding layers of those materials may be used. On the interlayer film330, a polycrystalline silicon films 340 are formed and patterned. Thepolycrystalline silicon films can be formed by the steps of forming a-Sifilms and, thereafter, annealing the a-Si films with an excimer laserand the like. On the polycrystalline silicon films 340, a gateinsulating film 350 is formed. For the gate insulating film, a film ofSiO₂ or SiN_(x), or a laminated film including layers of those materialsmay be used. On the gate insulating film 350, a layer of gate metal isformed and patterned, thereby forming gate electrodes 360. Examples ofthe gate metal include Cr, Al, and the like. During a period from theformation of the polycrystalline silicon films 340 to the formation ofthe gate electrodes 360, a process of injecting impurities into thesource and drain region of each TFT, a process of injecting lowconcentration impurities in order to form a LDD (Lightly Doped Drain)between the source and drain region and a channel forming region of eachTFT, a process such as channel dose to control a threshold value, and aprocess for activation may be performed. On the gate metal layer, aninterlayer film 370 is formed. For the interlayer film 370, a film ofSiO₂ or SiN_(x), of a laminated film including layers of those materialsmay be used. On the interlayer film 370, wiring metals 380 are made andpatterned. For the wiring metals 380, Al or an alloy containing it maybe used. In a pixel matrix region, pixel TFTs with the same structure asthat shown in FIG. 12 are formed. Although not illustrated, on the layerof wiring metal 380, interlayer films different from the above-mentionedone, pixel electrodes made of material for transparent electrodes suchas ITO (Indium Tin Oxide), and the like are formed. A structure abovethe wiring metals 380 may be modified appropriately depending on themode of a liquid crystal. Further, in each TFT, the wiring metal 380 iselectrically connected to the source and drain region of the TFT via acontact hole, and in the wiring region, if needed, the wiring metal 380is also electrically connected with the gate electrode 360 via a contacthole. It is desirable that the size of the light shielding film 320 ismade equal to or larger than that of the corresponding polycrystallinesilicon film because of the following reasons. That is, it is necessaryto make the light shielding film 320 overlap with a region where thegate electrode 360, on which a channel of a TFT is formed, and thepolycrystalline silicon film 340 overlap with each other in a planarview. In the case that the TFT has a LDD structure, it is furthernecessary to make the light shielding film 320 overlap with the LDDregion in a planar view. Further, it is necessary for the lightshielding film 320 to shield light irradiated to the TFT from an obliquedirection. For the TFTs constituting the control section 610, there isno need to necessarily dispose a light shielding film 320 beneath eachof the TFTs. That is, the control section 610 can include a TFTemploying a structure in FIG. 8 from which the light shielding film 320is omitted.

In each block in the gate driver, the voltage to be applied to the lightshielding film 320 disposed beneath each of the two TFTs constitutingthe output section 620 is a voltage becoming the same electric potentialas that of an output terminal in the corresponding block. However, inorder to suppress malfunction surely, it is preferable that the voltagebecoming the same electric potential as that of the output terminal isapplied to the light shielding film 320 disposed beneath TFT Tr1 (afirst TFT in which a gate voltage is stepped up or stepped down by abootstrap method), and that a voltage becoming the same electricpotential as that of the power source VGL (a source electrode of thecorresponding TFT) is applied to the light shielding film 320 disposedbeneath TFT Tr2 (a second TFT being different from the first TFT inwhich a gate voltage is stepped up or stepped down by a bootstrapmethod). Description is given to a structure to provide an electricpotential to the light shielding films 320 as stated above withreference to FIG. 9. FIG. 9 illustrates a cross section taken along theline IX-IX in FIG. 7, and shows an electrical connection between thelight shielding film 320 of TFT Tr1 and the wiring metal 380 forming theoutput terminal. On a region where the light shielding film 320extending from a position beneath TFT Tr1 overlaps with the wiring metal380 forming the output terminal in a planar view, a contact hole 325 isformed so as to penetrate through the interlayer film 330 used as a baselayer, the gate insulating film 350, and the interlayer film 370. Thelight shielding film 320 and the wiring metal 380 are electricallyconnected to each other via the contact hole 325. In TFT Tr2, similarly,the light shielding film 320 extending from a position beneath TFT Tr2is electrically connected via a contact hole to the wiring metal 380having the same electric potential as that of the power source VGL.

In the pixel matrix 200, the light shielding film 320 disposed beneatheach pixel TFT 300 may have a floating structure electrically notconnected to any one of wirings, or may be electrically connected so asto have the same electric potential as that of the gate line. However,in a liquid crystal display unit with the large number of pixels, it ispreferable that the light shielding film 320 disposed beneath each pixelTFT 300 is made in a floating state, in order to make the parasiticcapacitance of the gate line small.

FIG. 10 schematically shows a pattern of the light shielding films 320arranged on the TFT substrate 101 of the liquid crystal display unit inthe above-described structure. In the pixel matrix 200, the lightshielding films 320 are arranged in an isolated pattern such that theisolated light shielding films 320 is disposed at a position beneath acorresponding one of the pixel TFTs 300 and hides a semiconductor layerof the corresponding pixel TFT 300, when being viewed from the normaldirection of the TFT substrate 101. Also in the region of the outputsection 620 constituting the gate driver 600, the light shielding films320 are arranged in an isolated pattern such that the isolated lightshielding film 320 is disposed at a position beneath a corresponding oneof the TFTs constituting it and hides a semiconductor layer of thecorresponding TFT, when being viewed from the normal direction of theTFT substrate 101. However, in the region of the control section 610,since there is no need to necessarily dispose the light shielding film320 beneath each TFT, no light shielding films 320 are disposed in theexample shown in here. In a structure such that a protective elementconstituted with TFTs is arranged between the pixel matrix 200 and theoutput section 620, which is not illustrated, it is preferable todispose a light shielding film 320 at a position corresponding to theposition of each of the TFTs. Further, also in a structure that aprotective element constituted with TFTs is arranged on a data line inthe vicinity of the pixel matrix 200, it is preferable to dispose alight shielding film 320 at a position corresponding to the position ofeach of the TFTs. In addition to the protective element, also in astructure that other circuits employing TFTs such as an inspectioncircuit are arranged at a position irradiated with light through theopening section 107, it is preferable to dispose a light shielding films320 at a position corresponding to the position of each of the TFTs.

Next, description is given to operations of the gate driver withreference to a timing chart. FIG. 11 is a timing chart showing theoperations of one block of the gate driver illustrated in FIG. 6, whichis applicable to the liquid crystal display unit of the present example.Since this block is assumed as the n-th block among multiplecascade-connected blocks, an input signal indicated with a symbol of INin FIG. 6 becomes the output signal of the (n−1)th block. A period ofeach of T1 to T4 represents one horizontal period for writing videosignals into one pixel row of the liquid crystal display unit. The onepixel row mentioned here means a row of pixels connected to onearbitrary gate line shown in FIG. 3. Further, it is assumed that thehigh level of each of clocks CLK1 and CLK2 is the same electricpotential as that of the power source VGH and the low level is the sameelectric potential as that of the power source VGL.

In the period T1, since the input signal IN is at the low level, theelectric potential of a node C1 connected to the gate electrode of TFTTr1 is at the low level. Further, the electric potential of a node C2connected to the gate electrode of TFT Tr2 holds the high level. Theperiod T2 includes a period during which an input signal is at the highlevel and the clock CLK1 is also at the high level. Accordingly, TFT Tr3becomes in a conduction state, and the electric potential of a node C1rises to V1. Here, the electric potential of V1 is a value smaller by athreshold voltage of TFT Tr3 than the voltage of VGH. The node C1 is atthe high level and the node C2 is at the high level in this period,which means that each of TFTs Tr1 and Tr2 is in a conduction state. Onthe other hand, since the clock CLK2 is at the low level, an output OUTnis at the low level. In the period T2, in a period in which the clockCLK1 is at the high level, TFT Tr5 whose gate electrode is connected tothe node C1 is also in a conduction state. On the other hand, the nodeC2 is kept at the high level during a period in which the clock CLK1 isat the high level. With a change of the clock CLK1 to the low level, TFTTr4 becomes a non-conduction state, and the electric potential of thenode C2 changes to the low level together with the electric potential ofthe clock CLK1 since TFT Tr5 is made to keep the conduction state. Withthis, TFT Tr2 also changes from the conduction state to thenon-conduction state. However, the output OUTn is made to keep the lowlevel via TFT Tr1 all through in the period T2 since the clock CLK2 isat the low level. In the period T3, since the clock CLK1 is at the lowlevel, TFT Tr4 is in a non-conduction state. Even if TFT Tr5 is aconduction state, the node C2 is made to keep the low level since theclock CLK1 is at the low level, and TFT Tr2 is still in a non-conductionstate. Further, since the clock CLK1 is at the low level, TFT Tr3 is ina non-conduction state, and a node C1 is made in a floating state. Witha change of the clock CLK2 to the high level, the electric potential ofthe node C1 rises to V2 together with the rising of the electricpotential of the output OUTn because of a capacitive coupling by theparasitic capacitance between the gate and the sources of TFT Tr1 andthe capacitance Cb. The electric potential of V2 becomes a valueobtained by adding a voltage between VGH-VGL being a voltage amplitudeof the clock CLK2 to the electric potential of V1, whereby the electricpotential of V2 can be made higher than a value obtained by adding thethreshold voltage of TFT Tr1 to the electric potential of VGH.Accordingly, the electric potential V4 of the output OUTn is made torise finally to the electric potential of VGH. Thereafter, with a changeof the clock CLK1 to the low level, the electric potential of the outputOUTn also changes to the low level, and the electric potential of thenode C1 also lowers by the above-mentioned capacitive coupling. However,since the electric potential of the node C1 does not lower until TFT Tr1is made to a non-conduction state, the output OUTn reaches the electricpotential of VGL which is the low level electric potential of the clockCLK1. In the period T4, the clock CLK1 becomes the high level, each ofTFTs Tr3 and Tr4 becomes a conduction state, the electric potential ofthe node C1 becomes the electric potential of VGL which is the electricpotential of the input IN, and the electric potential of the node C2 ischarged to the high level by TFT Tr4. The electric potential V3 of thenode C2 at this time becomes a value smaller by the threshold voltage ofTFT Tr4 than the electric potential of VGH, and TFT Tr2 becomes aconduction state. As a result, the output OUTn is made to keep theelectric potential of VGL.

Such operations are performed sequentially in each of the multiplecascade-connected blocks, whereby the gate driver can perform anoperation to sequentially output pulses synchronized with the clocks.

As described in the above, there can be provided the liquid crystaldisplay unit of the present example, which does not cause image qualitydeterioration even under condition that it is irradiated with extremelystrong light, by using a liquid crystal panel with a small size.

Further, it becomes possible to protect occurrence of malfunction of thegate driver circuit more than the liquid crystal display unit shown inthe above-described embodiment.

The reasons why the liquid crystal display unit shown in the example hasthe similar effect as that in the embodiment are the same reasons shownin the embodiment. The reasons why it becomes possible to protectmalfunction of the gate driver circuit more than the liquid crystaldisplay unit shown in the embodiment are described hereafter.

In the liquid crystal display unit employing the structure that a gatedriver circuit is constituted with only TFTs of a single conductiontype, even when the output section 620 of the gate driver outputs asignal at a high level, the signal level may not become highsufficiently. Accordingly, malfunction may arise in that the output ofthe output section 620 cannot be transmitted to the next stage. Suchmalfunction may be caused by a situation that TFT Tr2 becomes aconduction state due to a certain reason together with a change of theTFT Tr1 to a conduction state. In the liquid crystal display unit shownin the embodiment, the same electric potential as that of the outputterminal is applied to a light shielding film disposed beneath each ofTFTs Tr1 and Tr2. It means that, when the output of this block becomes ahigh level, the electric potential of the light shielding film alsobecomes the high level. With a change of the electric potential of aconductor disposed at the back-channel side of the n type TFT to a highlevel, a threshold voltage changes in a direction in which the thresholdvoltage becomes low. Here, if the threshold voltage of TFT Tr2 isrelatively small due to variation in manufacturing, an electric currentmay flow between the source and the drain due to the influence of theelectric potential of the light shielding film even under the conditionthat the gate voltage is at a low level. Such a situation makes theelectric potential of the output smaller than the electric potential ofVGH because the electric potential of the output is divided at anelectric potential between the respective electric potentials of VGH andVGL. In this way, in a series of blocks in which the threshold voltageof TFT Tr2 is small, the output voltage decreases gradually for eachtime when the output is transferred to the next block, and finally, theoutput voltage becomes so small that it cannot be transferred.

In the liquid crystal display unit of the present example, differentelectric potentials are applied to light shielding films disposedseparately beneath the respective TFT Tr1 (first TFT) and TFT Tr2(second TFT) constituting the output section are provided. The sameelectric potential as that of the output terminal of the output sectionis applied to the light shielding film disposed beneath TFT Tr1 (firstTFT) in which its drain terminal is connected to the clock line. On theother hand, the electric potential of the power source VGL is applied tothe light shielding film disposed beneath TFT Tr2 (second TFT) in whichits source terminal is connected to the power source VGL. Accordingly, achange of the voltage of an output terminal to a high level merelycauses a change of only the threshold voltage of TFT Tr1 in thedirection which the threshold voltage becomes small, and it does notmake the electric potential of the output terminal lower. Therefore, oneof the modes of malfunction does not occur, which makes it difficult tocause malfunction.

In the example shown hitherto, all the pixel TFTs and all the TFTsconstituting the gate driver are n-type TFTs. However, only p-type TFTsmay be used for them. In the case of using p-type TFTs, the electricpotential of the output terminal of the output section may be applied toa light shielding film disposed beneath a TFT which constitutes anoutput section of a gate driver and in which its drain terminal isconnected to a clock line, and the electric potential of the powersource VGH may be applied a light shielding film disposed beneath a TFTin which its source terminal is connected to a power source VGH. As forthe connecting relationship of TFTs constituting a control section, theTFTs may be connected so as to reverse the relationship between thepower sources VGH and VGL, and control clocks may be configured toreverse the relationship between the high level and the low level.

Further, in either of the case that the gate driver is constituted withonly n-type TFTs and the case that that is constituted with only p-typeTFTs, the control section can employ a circuit constitution other thanthose shown in FIG. 4 and FIG. 6. For example, the control section mayemploy a constitution in which a function to switch over the scanningdirection of a gate driver is added, or a constitution to control withthree phase or more clocks. Furthermore, also the output section mayemploy a constitution with two or more TFTs in each of which a sourceterminal is connected to a power source. In such a case, in all the TFTsin each of which a source terminal is connected to the power source, theelectric potential of the power source is applied to a light shieldingfilm disposed beneath a corresponding TFT, and a voltage of the outputterminal is applied to a light shielding film disposed beneath a TFT inwhich a drain terminal is connected to a clock line.

Namely, features of the liquid crystal display unit of theabove-described embodiment and example are as follows. An electricpotential to be applied to light shielding films formed beneath of TFTsin the output section is set as follows. The output section includes aTFT (first TFT) in which a clock line is connected to at least its drainterminal and the electric potential of its gate terminal is stepped upor stepped down in comparison with a range of a power source voltage bya bootstrap effect, and a TFT (second TFT) in which its source terminalis connected to the power source. In the output section, the electricpotential to be applied to a light shielding film is changed between alight shielding film disposed beneath the first TFT and a lightshielding film disposed beneath the second TFT. In particular, theelectric potential of the output terminal is applied to the lightshielding film disposed beneath a TFT (first TFT) to which the electricpotential of its gate terminal is stepped up or stepped down by abootstrap effect. Further, a position covered with a package member isset such that a light shielding film is disposed beneath only a TFTconstituting the output section and a light shielding film is not neededto be disposed beneath a TFT constituting the control section.

The present invention should not be limited to the above-mentionedembodiments and examples, and unless any change deviates from theintention of the present invention, such a change may be madeappropriately for the constitution of the liquid crystal display unit.

The liquid crystal display units of the above-described embodiments andexamples of the present invention can be applied to a display unit inwhich a liquid crystal display unit is irradiated with extremely stronglight, such as a liquid crystal projector and a head-up display.

The invention claimed is:
 1. A liquid crystal display unit comprising:an insulating substrate; a counter insulating substrate facing theinsulating substrate; a liquid crystal put between the insulatingsubstrate and the counter insulating substrate; a pixel matrix includinga plurality of pixels each including a pixel capacitor and a pixel TFT;and a peripheral circuit including a control section and an outputsection, for driving a gate line of the pixel TFT in each of the pixels,each of the control section and the output section including TFTs,wherein the pixel matrix and the peripheral circuit are integrallyformed in one body and formed on the insulating substrate, the outputsection is located closer to the pixel matrix than the control sectionwhen being viewed from a normal direction of the insulating substrate,the pixel TFTs of the pixels and the TFTs in the peripheral circuit havea top-gate structure, and the liquid crystal display unit furthercomprises a light shielding metal disposed at an insulating-substrateside of the pixel TFT in each of the pixels, and a light shielding metaldisposed at an insulating-substrate side of each of the TFTs at least inthe output section among the TFTs in the peripheral circuit.
 2. Theliquid crystal display unit of claim 1, wherein the control sectionincludes a TFT at the insulating-substrate side of which a lightshielding metal is not disposed.
 3. The liquid crystal display unit ofclaim 1, wherein the TFTs in the peripheral circuit are TFTs of a sameconductivity type, the TFTs in the output section includes a first TFTwhose gate voltage is to be stepped up or stepped down by a bootstrapmethod, and the light shielding metal formed on the insulating-substrateside of the first TFT has a same electric potential as an electricpotential of an output terminal of the output section.
 4. The liquidcrystal display unit of claim 3, the TFTs in the peripheral circuitincludes a second TFT at the insulating-substrate side of which a lightshielding metal is disposed, the second TFT being different from thefirst TFT, and the light shielding metal disposed at theinsulating-substrate side of the second TFT has a same electricpotential as that of a source electrode of the second TFT.
 5. The liquidcrystal display unit of claim 1, wherein the light shielding metaldisposed at the insulating-substrate side of the pixel TFT in each ofthe pixels, hides a semiconductor layer of the corresponding pixel TFT,when being viewed from the normal direction of the insulating substrate,and the light shielding metal disposed at the insulating-substrate sideof each of the TFTs in at least the output section among the TFTs in theperipheral circuit, hides a semiconductor layer of the correspondingTFT, when being viewed from the normal direction of the insulatingsubstrate.
 6. The liquid crystal display unit of claim 1, furthercomprising a package member made of a material which does not transmitlight, wherein the package member covers the insulating substrate andthe counter insulating substrate, and includes an opening section formedthereon, and an edge surface of the opening section overlaps with theoutput section when being viewed from the normal direction of theinsulating substrate.
 7. The liquid crystal display unit of claim 6,wherein the edge surface of the opening section is located in a middleof a pixel-matrix-side edge of the control section and aperipheral-circuit-side edge of the pixel matrix when being viewed froma normal direction of the insulating substrate.